1. Field of the Invention
The present invention relates generally to a device for brewing coffee, and more particularly to an improved coffee maker specially designed for installation in an aircraft, which coffee maker operates automatically, is substantially lighter, and brews coffee faster than conventional aircraft coffee makers known in the art.
For virtually as long as there has been commercial air travel, stewardesses have been giving passengers complimentary drinks, including coffee and hot tea. In early airplanes, since the flights were relatively short and the cabins were small, it was sufficient to carry on thermoses of brewed coffee, and to merely dispense it during the flight. However, as trips grew in duration, and as the size of aircraft steadily increased, it became increasingly impractical to carry on sufficient hot coffee for a flight.
Thus was born the first coffee maker in an aircraft, which was only somewhat modified from a conventional drip coffee maker. Over the years several modifications have been made in the aircraft coffee brewing system, most of which have been due to safety considerations. The coffee makers are required by FAA regulations to be securely fastened in place in a bay which was originally used to hold a refillable water dispensing tank. The coffee maker bay has a rail mount to which a coffee maker is fastened securely after the coffee maker is slid into the coffee maker bay. This prevents the coffee maker from being thrown from its place during turbulence encountered during a flight.
Another safety requirement is the provision that the coffee pot or server be securely retained in the coffee maker whenever it is placed there. This requirement prevents the server itself, which may be filled with hot coffee, from being thrown from the coffee maker and causing severe burns to the galley crew or even to passengers. It will be recognized at once by those skilled in the art that the mechanism used to retain the server in the coffee maker must be easy to operate, preferably being operable with the same hand used to remove the server from the coffee maker.
An additional difference of aircraft coffee makers over domestic coffee makers is that the aircraft coffee makers are operated at high altitudes with cabin pressures substantially below sea level air pressure. This results in water having a substantially lower boiling point, typically less than 200 degrees Fahrenheit. As such, aircraft coffee makers must be designed to heat water to a point below the typical coffee maker temperature of 205 degrees Fahrenheit, plus or minus five degrees.
Another requirement of the aircraft coffee maker is that it operate on the electrical voltage available in the aircraft. Most aircraft use 208 Volt 400 Hertz three phase power, with only a limited amount of 110 Volt power being available (typically for uses such as to power electric shavers in the aircraft lavatories). It will at once be realized by those skilled in the art that a coffee maker requires substantial wattage when brewing coffee. Even so, most available aircraft coffee makers operate only on single phase power, making them inconvenient to say the least. It is accordingly an objective of the present invention that it operate on 208 Volt 400 Hertz three phase power for brewing coffee.
The disadvantages inherent in existing aircraft coffee makers are best illustrated through a description of their typical brewing cycle. A fill valve is opened to fill the brewing tank with water (just as a conventional domestic coffee maker must be filled with water). This is typically a manual operation which must be supervised by the galley crew. In many aircraft coffee makers, there is also a manual vent valve which must be opened to vent the brewing tank. After filling the brewing tank, the fill valve is turned off and the vent valve is closed.
The coffee maker is turned on, and the water begins to heat. While some of the coffee makers will send the heated water to a brew nozzle over a tray containing the coffee, which is located over the server, others have a hot water valve which may be used to divert the hot water to the side through a nozzle. This hot water valve diverts water to the nozzle for use in making hot tea. It may thus be seen that conventional aircraft coffee makers have a brewing tank, and as many as many as three manually actuated valves.
This makes the coffee brewing operation an excessively manual operation which requires a substantial amount of galley crew time. It is a primary objective of the present invention to automate the coffee brewing process to the maximum extent possible. It is also an objective of the present invention to eliminate as much weight in the coffee maker as possible. This will result in valuable fuel savings, since each additional pound of equipment carried presently costs as much as $350 per year in additional fuel burned.
A conventional aircraft coffee maker such as those presently known in the art requires approximately seven to seven and one-half minutes to brew a 34-36 ounce server of coffee. This is greater than one minute per cup to brew the coffee, and is unacceptable since it frequently results in delays in serving passengers. Accordingly, it is an additional objective of the present invention to speed up the brewing process as much as possible. Since most of the time required in the brewing process is the time required to heat the water, it is thus an objective of the present invention to heat the water substantially faster than is done in existing aircraft coffee maker designs.
An additional problem which may occur with existing aircraft coffee makers is damaging them by operating them without water in the brewing tank. In the case of those which have a thermostat, if the thermostat fails the coffee maker will overheat, damaging the coffee maker. Another potential problem occurring with a failed thermostat is the potential of overheating the water beyond the lowered boiling point mentioned above. The potential for a bursting brewing tank is possible, which could cause both steam burns of the galley crew and discomfort to the passengers. It is therefore a first additional objective of the present invention to provide backup safety monitoring of a possible overheating situation, and a second additional objective to provide an alternate flow path for heated water in the event of a high pressure situation occurring for any reason.
It is thus a further objective of the present invention to provide an enhanced aircraft coffee maker having all of the above advantages and objectives which is easy to operate and which will be desirable to galley crew personnel. A final objective is that the improved aircraft coffee maker of the present invention be as easy and inexpensive to manufacture as possible, thereby giving it an economic advantage in marketing it against competing designs. Finally, it is desirable that the present invention provide all of the aforesaid advantages and objectives without resulting in any significant disadvantage.